a simple calculated grade software with arrayList

demo.java

import java.util.Scanner;

public class demo {
	
	@SuppressWarnings("resource")
	public static void main(String[] args) {
		gradeModel gradeF = new gradeModel(0, 49, "F");
		gradeModel gradeD = new gradeModel(50, 59, "D");
		gradeModel gradeC = new gradeModel(60, 69, "C");
		gradeModel gradeB = new gradeModel(70, 79, "B");
		gradeModel gradeA = new gradeModel(80, 100, "A");
		
		gradeController listGrades = new gradeController();
		listGrades.addGrade(gradeF);
		listGrades.addGrade(gradeD);
		listGrades.addGrade(gradeC);
		listGrades.addGrade(gradeB);
		listGrades.addGrade(gradeA);
		
		Scanner input = new Scanner(System.in);
		int score = input.nextInt();
		String calculatedGrade = listGrades.findGrade(score);
		System.out.print("Your grade is "+calculatedGrade);
	}
}

gradeController.java

import java.util.ArrayList;

public class gradeController {
	public ArrayList<gradeModel> listGrades = new ArrayList<gradeModel>();
	
	public void addGrade(gradeModel grade) {
		this.listGrades.add(grade);
	}
	
	public String findGrade(int score) {
		for(gradeModel grade: listGrades) {
			if(score >= grade.minimum && score <= grade.maximum) {
				return grade.grade;
			}
		}
		return "Invalid score";
		
	}

}

gradeModel.java

public class gradeModel {
	public int minimum;
	public int maximum;
	public String grade;
	
	gradeModel(int min,int max,String grade){
		this.minimum = min;
		this.maximum = max;
		this.grade = grade;
	}
}